Steam Pipeline Insulation Conditions-Microporous Insulation Boards

1. Steam Pipeline Insulation Conditions:

Insulation Points: Conventional island steam turbines, pneumatic pumps, pressure vessels, main steam pipelines, bypass steam pipelines, reheated steam pipelines, water supply and drainage pipelines, etc., in power plants and nuclear power stations.

Medium Temperatures: Main steam: 280-320°C, mostly ≤300°C; Reheated steam: 250-280°C; Other: ≤250°C.

2. Comparison Between Traditional Insulation Materials and Microporous Insulation Felt:

Traditional Insulation Materials: Composite silicate felt/pipe shells, high-temperature glass wool felt/pipe shells, rock wool. Due to environmental and personnel health considerations, the usage of rock wool has gradually decreased.

Microporous Insulation Felt: Microporous insulation material with extremely low thermal conductivity and effective waterproof performance. Specific comparisons with traditional insulation materials are outlined in Table 1.

3. Microporous Insulation Felt Insulation Solution and Economic Benefits

Taking the example of the main steam pipeline (straight section) with an outer diameter of 325mm and a temperature of 300°C, an analysis of the usage thickness, insulation performance, and economic benefits of Microporous insulation felt compared to traditional insulation materials is provided below:

I) Insulation Solutions:

Option 1:

Utilize Microporous insulation felt as the primary insulation material, with an additional protective layer of 1.2mm aluminum alloy sheet on the outer surface.

Options 2 and 3:

Employ Microporous insulation felt as the main insulation material, supplemented by composite silicate felt for auxiliary insulation.

Apply a protective layer of 1.2mm aluminum alloy sheet on the outer surface. Insulation material thickness is detailed in Table 2.

II) Insulation Performance:

For the composite silicate used within 0-3 years, the phenomenon of reduced insulation performance due to settling can be disregarded. Based on GB/T 8175-2008 "Testing and Evaluation of Insulation Performance for Equipment and Pipelines," the calculation of heat dissipation loss and energy-saving efficiency is presented in Table 3.

Table 3: Insulation Performance for Each Option

The above calculations are based on environmental conditions with a temperature of 25°C and minimal wind. In the presence of wind, the surface heat dissipation loss will be more noticeable due to the higher surface temperature of the composite silicate felt in traditional insulation.

As time progresses, the settling of the composite silicate results in a deterioration of insulation performance.

Table 4: Insulation Performance of Each Option After 3 Years of Use

Usage Time: 3-6 Years

Usage Time: 6-10 Years

These calculations are based on a usage period of 3-10 years, demonstrating the surface temperature, pipe heat flux density, line heat flux density, and energy-saving efficiency for each insulation option. As time increases, the settling of composite silicate in traditional insulation leads to a decline in insulation performance.

Table 5: Insulation Material Usage for Each Option

Table 6: Total Cost for Each Option (Unit: Ten Thousand Yuan)

Auxiliary materials include fiberglass mesh, metal sealing glue, and other materials. Construction costs include expenses related to renting or purchasing various tools.

For the period of 0-3 years:

For the period of 3-6 years:

For the period of 6-10 years:

The above data is calculated based on an electricity cost of 0.5 yuan/KWh. Assuming the replacement of composite silicate in the insulation materials every 5 years, the economic benefits for each scheme over 10 years are as follows:

4. Construction Method of Nanoporous Insulation for Pipeline Insulation

(1)When constructing double-layer and multi-layer nanoporous insulation felt, each layer should be bundled layer by layer. It should be laid with a staggered seam and a pressing seam, and the lap joint position should not be arranged within a 45° range of the vertical centerline of the pipeline.

(2)Determine the required lengths of the two layers separately through direct wrapping measurements. The overlap size along the pipeline direction is 10-20mm

(3)Affix the cut nanoporous insulation felt tightly to the pipeline. First, fix the starting end with galvanized iron wire (Φ0.5mm or Φ1mm) or high-temperature tape, and then fix the other end of the aerogel insulation felt on the pipeline in the same way.

(4)Use fiberglass mesh to fix the material on the pipeline by spiral winding. The winding direction should be consistent with the direction of the material overlap, and the bundling should be smooth. The overlap size of the fiberglass mesh is half the width. It is recommended to use fiberglass mesh with a width of 10-30cm.

(5)The circumferential joints of adjacent layers should be bundled with a staggered width of half the width of the nanoporous insulation felt. Finally, apply the metal protective layer.

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